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Hershel Jick

Publications and source records attributed to Hershel Jick.

At least 19 recordsLinked to original sources

Cerebral venous sinus thrombosis in users of four hormonal contraceptives: levonorgestrel-containing oral contraceptives, norgestimate-containing oral contraceptives, desogestrel-containing oral contraceptives and the contraceptive patch.

BACKGROUND: It has been suggested that the risk for cerebral venous sinus thrombosis (CVST) may be greater among users of the contraceptive patch than among users of oral contraceptives (OCs). METHODS: From the PharMetrics database, we identified women aged 15-44 years who filled at least one prescription for either the contraceptive patch or desogestrel-containing, norgestimate-containing or levonorgestrel-containing OCs to assess the risk of CVST. The person-time of current exposure to each study drug, as well as the incidence rates (IRs) and incidence rate ratios (IRRs) of CVST, was calculated. RESULTS: We identified over 1 million users of the four study drugs. There were five cases of CVST among current users of desogestrel, seven cases among current users of norgestimate, two cases among current users of levonorgestrel and none among current users of the contraceptive patch. The IRs per 100,000 woman-years were 2.7 [95% confidence interval (95% CI)=0.9-6.3], 1.6 (95% CI=0.7-3.3), 0.7 (95% CI=0.1-2.4) and 0.0 (95% CI=0.0-4.8), respectively, in users of desogestrel, norgestimate, levonorgestrel and the contraceptive patch. There were two women who had CVST while not currently taking a hormonal contraceptive (IR=0.4 per 100,000 woman-years; 95% CI=0.1-1.3). The IRRs were 4.0 (95% CI=0.7-42.4) for desogestrel-containing versus levonorgestrel-containing OCs, and 2.4 (95% CI=0.5-24.0) for norgestimate-containing versus levonorgestrel-containing OCs. The IRR for the patch could not be calculated. CONCLUSIONS: There is no evidence of an increased risk of CVST in users of the contraceptive patch compared to users of levonorgestrel-containing OCs.

Administration, Cutaneous↗

Antibiotic use and risk of multiple sclerosis.

Some reports suggest that bacteria, including Chlamydophila pneumoniae, could be involved in the etiology of multiple sclerosis. If that is true, persons who used antibiotics active against these bacteria, compared with nonusers, might be at lower risk of multiple sclerosis. Using a 1993-2000 case-control study nested in the United Kingdom-based General Practice Research Database cohort, the authors identified 163 multiple sclerosis cases who were followed up for at least 3 years before their first symptoms (the index date). Up to 10 controls matched to the cases by age, sex, general practice, and time in the cohort were selected. Exposure to antibiotics was assessed through computerized medical records. Overall antibiotic use or use of antibiotics against C. pneumoniae was not associated with multiple sclerosis risk. However, use of penicillins in the 3 years before the index date decreased the risk of developing a first attack of multiple sclerosis (odds ratio=0.5, 95% confidence interval: 0.3, 0.9 for those who used penicillins for >or=15 days compared with no use). In conclusion, use of antibiotics active against C. pneumoniae was not associated with a decreased risk of short-term multiple sclerosis. The observed lower risk of multiple sclerosis for penicillin users needs to be confirmed in other populations.

Adult↗

Risk of nonfatal venous thromboembolism with oral contraceptives containing norgestimate or desogestrel compared with oral contraceptives containing levonorgestrel.

CONTEXT: Previous studies have reported that users of the "third-generation" oral contraceptives (OCs) containing the progestins gestodene and desogestrel have about twice the risk for venous thromboembolism (VTE) compared to users of older OCs containing levonorgestrel. Estimates of the risk for VTE among users of norgestimate-containing OCs compared to other OCs, however, are lacking. OBJECTIVE: The purpose of this study is to obtain quantitative information on the risk of nonfatal VTE in women using OCs containing either norgestimate or desogestrel in comparison with women taking OCs containing levonorgestrel. DESIGN, SETTING AND PARTICIPANTS: Based on information from PharMetrics, a United States-based company that collects and records information on claims paid by managed care plans, we used a nested case-control study design to estimate relative risks of nonfatal VTE among 15- to 39-year-old current users of OCs containing norgestimate with 35 microg of ethinyl estradiol (EE), desogestrel with 30 microg of EE or levonorgestrel with 30 microg of EE, both monophasic and triphasic preparations, during the period January 2000 to March 2005. Cases were women with a well-documented VTE of uncertain origin that was diagnosed in current users of a study drug. Up to four controls were closely matched to each case by age and calendar time, and odds ratios (ORs) were calculated using conditional logistic regression comparing the risk of VTE among users of the three contraceptives. We also estimated and compared the incidence rates for all three OCs. RESULTS: Based on 281 newly diagnosed idiopathic cases of VTE and 1055 controls, we found that the adjusted ORs for nonfatal VTE comparing norgestimate- or desogestrel-containing OC users to users of levonorgestrel-containing OCs were 1.1 [95% confidence interval (CI), 0.8-1.6] and 1.7 (95% CI, 1.1-2.4), respectively. The incidence rates of VTE were 30.6 (95% CI, 25.5-36.5), 53.5 (95% CI, 42.9-66.0) and 27.1 (95% CI, 21.1-34.3) per 100,000 woman-years for users of norgestimate-, desogestrel- and levonorgestrel-containing OCs, respectively. The incidence rate ratios for norgestimate-containing OCs compared to levonorgestrel-containing OCs and desogestrel-containing OCs compared to levonorgestrel-containing OCs were 1.1 (95% CI, 0.8-1.5) and 2.0 (95% CI, 1.4-2.7), respectively. CONCLUSIONS: The risk of nonfatal VTE among users of desogestrel-containing OCs is significantly elevated compared to that of levonorgestrel-containing OCs. The risk of VTE in users of norgestimate-containing OCs was closely similar to that of users of levonorgestrel-containing OCs.

Adolescent↗

Risk of nonfatal venous thromboembolism in women using a contraceptive transdermal patch and oral contraceptives containing norgestimate and 35 microg of ethinyl estradiol.

CONTEXT: There is concern that a new transdermal contraceptive patch containing ethinyl estradiol (EE) and the progestin norelgestromin increases the risk for venous thromboembolism (VTE) compared to previously marketed oral contraceptives (OCs). OBJECTIVE: Quantitative information was obtained on the risk of nonfatal VTE in women using the contraceptive patch in comparison to women using OCs, norgestimate (either monophasic or triphasic) and 35 microg EE (norgestimate-35), an OC that has been marketed for over a decade. DESIGN, SETTING AND PARTICIPANTS: Nested case-control design based on information from PharMetrics, a US-based company that collects and organizes information on claims paid by managed care plans. The study was nested among all women aged 15 to 44, who started either the contraceptive patch or norgestimate-35 after April 1, 2002. Cases were women with current use of one of these two study drugs and a documented diagnosis of VTE in the absence of identifiable clinical risk factors (idiopathic VTE). Up to four controls were matched to each case by age and calendar time. MAIN OUTCOME MEASURES: Odds ratios (ORs) comparing the risk of nonfatal VTE in new users of the two contraceptives and incidence rates of nonfatal VTE for new users of each of the study contraceptives. RESULTS: We identified 68 newly diagnosed, idiopathic cases of VTE in the study population. In the case-control analysis, the OR comparing the contraceptive patch to norgestimate-35 was 0.9 (95% CI 0.5-1.6). The overall incidence rate for VTE was 52.8 per 100,000 women-years (95% CI 35.8-74.9) among users of the contraceptive patch and 41.8 per 100,000 women-years among users of norgestimate-35 (95% CI 29.4-57.6), and the age-adjusted VTE incidence rate ratio (IRR) for current use of the contraceptive patch vs. norgestimate-35 was 1.1 (95% CI 0.7-1.8). CONCLUSIONS: The risk of nonfatal VTE for the contraceptive patch is similar to the risk for OCs containing 35 microg ethinylestradiol and norgestimate.

Administration, Cutaneous↗

Epidemiology of anaphylaxis: findings of the American College of Allergy, Asthma and Immunology Epidemiology of Anaphylaxis Working Group.

OBJECTIVE: To improve understanding of the epidemiology of anaphylaxis. DATA SOURCES: We performed a qualitative review by hand of the major epidemiology studies of anaphylaxis. This review was restricted to articles in the English language. STUDY SELECTION: Articles chosen were selected by the committee and dated back to 1968. There was no specific criterion used for selection except the determination of the members of the committee. RESULTS: Data on anaphylaxis incidence and prevalence are sparse and often imprecise. Findings are based on diverse study designs and are not entirely comparable. These factors have contributed to widely varying estimates of the frequency of this important condition. The roundtable discussion led to an improved estimation of the frequency of anaphylaxis: approximately 50 to 2,000 episodes per 100,000 persons or a lifetime prevalence of 0.05% to 2.0%. The largest number of incident cases is among children and adolescents. In addition to underdiagnosis, we noted undertreatment, especially for those at highest risk (ie, those without immediate access to treatment with epinephrine). CONCLUSIONS: Anaphylaxis is a relatively common problem, affecting up to 2% of the population. Further data on epinephrine dispensing could improve current estimates. Another way to improve current understanding would be through better population-based study designs in different geographic regions. A recurring theme was the importance of broader access to self-injectable epinephrine for high-risk populations. An improved epidemiologic understanding of this disorder would aid ongoing efforts to reduce morbidity and mortality from anaphylaxis and could provide important clues for primary prevention.

Anaphylaxis↗

Nonsteroidal antiinflammatory drugs and acute myocardial infarction in patients with no major risk factors.

STUDY OBJECTIVE: To assess the risk of long-term use of five nonsteroidal antiinflammatory drugs (NSAIDs)--rofecoxib, celecoxib, ibuprofen, naproxen, and diclofenac--in relation to acute myocardial infarction. DESIGN: Five separate nested case-control studies, one for each NSAID, designed to minimize important biases present in other observational studies. Setting. University-affiliated research program. Data Source. The United Kingdom General Practice Research Database (GPRD). MEASUREMENTS AND MAIN RESULTS: We identified all people in the GPRD aged 30-79 years who had a first recorded prescription for rofecoxib, celecoxib, ibuprofen, naproxen, or diclofenac after January 1, 1999. Cases of newly diagnosed, first-time acute myocardial infarction were then identified from the study population, along with matched control subjects. Relative risk estimates for acute myocardial infarction in patients with no recorded major clinical risk factors for acute myocardial infarction were determined for each NSAID according to receipt of 2-4, 5-9, 10-19, or 20 or more prescriptions compared with receipt of only 1 prescription. Results were adjusted for relevant variables possibly related to the risk for acute myocardial infarction. No material elevation of risk according to the number of prescriptions received for ibuprofen or naproxen was noted. However, a substantial increased risk similar to that found in clinical trials was noted in patients who received 10 or more prescriptions for rofecoxib, celecoxib, or diclofenac. CONCLUSION: Extensive use of rofecoxib, celecoxib, and diclofenac increases the risk of acute myocardial infarction, but similar use of ibuprofen and naproxen does not.

Acute Disease↗

Cigarette smoking and the progression of multiple sclerosis.

An increased risk of multiple sclerosis among smokers has been found in several prospective epidemiological studies. The association between smoking and progression of multiple sclerosis has not been examined. We identified patients who had a first multiple sclerosis diagnosis recorded in the General Practice Research Database (GPRD) between January 1993 and December 2000. Their diagnosis and date of first symptoms were confirmed through examination of medical records. Smoking status was obtained from the computer records. To assess the association between smoking and risk of multiple sclerosis, we conducted a case-control study nested in the GPRD. Up to 10 controls per case were randomly selected, matched on age, sex, practice, date of joining the practice and availability of smoking data. To assess the association between smoking and progression of multiple sclerosis, we conducted a cohort study of multiple sclerosis cases with a relapsing-remitting onset. Our nested case-control study included 201 cases of multiple sclerosis and 1913 controls. The odds ratio [95% confidence interval (CI)] of multiple sclerosis was 1.3 (1.0-1.7) for ever smokers compared with never smokers. Our cohort study included 179 cases with a mean (median) length of follow-up of 5.3 (5.3) years. The hazard ratio of secondary progression was 3.6 (95% CI 1.3-9.9) for ever smokers compared with never smokers. These results support the hypothesis that cigarette smoking is associated with an increased risk of multiple sclerosis, and suggest that smoking may be a risk factor for transforming a relapsing-remitting clinical course into a secondary progressive course.

Adult↗

Recent use of oral contraceptives and the risk of multiple sclerosis.

BACKGROUND: Exogenous estrogens affect the onset and clinical course of experimental allergic encephalomyelitis. Oral contraceptives, a frequent source of exogenous estrogens in humans, could have a role in the development of multiple sclerosis (MS). OBJECTIVE: To examine whether recent oral contraceptive use and pregnancy history are associated with the risk of MS. DESIGN AND SETTING: A case-control study nested in the General Practice Research Database. This database contains prospective health information (drug prescriptions and clinical diagnoses) on more than 3 million Britons who are enrolled with selected general practitioners. PARTICIPANTS: One hundred six female incident cases of MS, younger than 50 years, with at least 3 years of continuous recording in the General Practice Research Database before the date of first symptoms (index date), identified between January 1, 1993, and December 31, 2000, and 1001 controls matched on age, practice, and date of joining the practice. Main Outcome Measure Incidence of first symptoms of MS, confirmed through medical records. RESULTS: The incidence of MS was 40% lower (odds ratio, 0.6; 95% confidence interval, 0.4-1.0) in oral contraceptive users compared with nonusers during the previous 3 years. The risk of MS increased in the 6 months after pregnancy (odds ratio, 2.9, 95% confidence interval, 1.2-6.6), but it was not otherwise related to parity. CONCLUSIONS: The hormonal changes that occur during oral contraceptive use and pregnancy may be associated with a short-term reduction in the risk of MS, and the postpartum period may be associated with a short-term increase in the risk of MS.

Adolescent↗

Cesarean delivery in the United Kingdom: time trends in the general practice research database.

OBJECTIVE: To estimate recent temporal trends in delivery by cesarean during the past decade and the proportion of vaginal deliveries after prior caesarean in the United Kingdom. METHODS: We conducted a cohort study using information from the General Practice Research Database. We identified all women with 1 or more deliveries between January 1990 and December 1999 and determined the method(s) of delivery. We estimated the proportion of women with vaginal delivery after cesarean in a subcohort who had at least 3 years of follow-up. RESULTS: We identified 39,938 cesareans among 271,663 deliveries (14.7%), with an increase from 12.5% in 1990 to 18.3% in 1999. The proportion of cesarean deliveries increased with age and increased over time in all age groups except women aged younger than 20 years. Among 26,480 women with a caesarean delivery between 1990 and 1996, 7,649 (28.9%) had a subsequent delivery. The proportion of vaginal delivery after prior cesarean decreased from 45% in 1991 to 37% in 1999. CONCLUSION: Cesarean deliveries increased as a proportion of all deliveries in the United Kingdom during the past decade, and the proportion of vaginal delivery after prior cesarean decreased. Still, the proportion of cesarean deliveries is lower and the proportion of vaginal deliveries after prior cesarean is higher in the United Kingdom than in the United States. LEVEL OF EVIDENCE: II-2.

Adult↗

Antibiotics and the risk of breast cancer.

BACKGROUND: Two recent studies found a positive association between antibiotic use and the risk of breast cancer. METHODS: Using information from the U.K. General Practice Research Database, we identified 1268 cases of incident breast cancer (40- to 79-year-old women diagnosed in 1987 to 2002 who had at least 6 years of history recorded in the General Practice Research Database) and 6291 female controls matched to the cases on age, general practice, and duration of history recorded in the General Practice Research Database. We ascertained antibiotic prescriptions (penicillins, cephalosporins, sulfonamides, macrolides, tetracyclines, quinolones, metronidazole, and nitrofurantoin) recorded up to 1 year before the index date. RESULTS: Odds ratios (95% confidence intervals) of breast cancer for 0, 1-50, 51-100, 101-500, and 501 or more cumulative days of antibiotic use were 1.0 (reference), 1.0 (0.9-1.2), 0.9 (0.7-1.2), 0.9 (0.7-1.3), and 1.2 (0.6-2.4). CONCLUSIONS: These data do not support the hypothesis that antibiotic use is associated with an increased risk of breast cancer.

Adult↗

Risk of cholestatic liver disease associated with flucloxacillin and flucloxacillin prescribing habits in the UK: cohort study using data from the UK General Practice Research Database.

AIMS: To provide additional quantification of the risk of flucloxacillin-related liver disease and to describe time trends in flucloxacillin prescribing in the UK. METHODS: This was a cohort study using data from the UK General Practice Research Database. We identified patients with a first-time prescription for flucloxacillin or, for comparison, oxytetracycline from 1992 to 2002 and cases who developed clinically documented cholestatic liver disease of uncertain origin after first-time use of these drugs. We also determined the annual frequency of first-time use of flucloxacillin from 1991 to 2000. RESULTS: We identified 283 097 and 131 189 first-time users of flucloxacillin and oxytetracycline, respectively. The risk of cholestatic liver disease per 100 000 first-time users was 8.5 (95% CI 5.4, 12.6) in the 1-45 days and 1.8 (95% CI 0.6, 4.1) in the 46-90 days after starting flucloxacillin, and 0.8 (95% CI 0.02, 4.3) in the 1-45 days after starting oxytetracycline. The frequency of first-time use of flucloxacillin remained stable between 1991 and 2000. CONCLUSIONS: Flucloxacillin is now established as an important cause of cholestatic liver disease. Warnings about the risk have not had an impact on prescribing practices in the UK, where it remains the predominantly prescribed antistaphylococcal oral antibiotic. This situation in the UK is in sharp contrast to regulatory actions and changes in prescribing habits in Australia after identification of the risk of cholestasis associated with flucloxacillin, and to the predominant use of the alternative drug dicloxacillin in the USA.

Aged↗

Time trends in eating disorder incidence.

BACKGROUND: During the years 1988-1993 the primary care incidence of anorexia nervosa in the UK remained stable, but the incidence of bulimia nervosa increased threefold. AIMS: To determine whether the incidence of anorexia nervosa remained stable, and that of bulimia nervosa continued to increase, in the years 1994-2000. METHOD: The General Practice Research Database was screened for new cases of anorexia and bulimia nervosa between 1994 and 2000. Annual incidence rates were calculated for females aged 10-39 years and compared with rates from the previous 5 years. RESULTS: In 2000 primary care incidence rates were 4.7 and 6.6 per 100,000 population for anorexia and bulimia nervosa, respectively. The incidence of anorexia nervosa remained remarkably consistent over the period studied. Overall there was an increase in the incidence of bulimia, but rates declined after a peak in 1996. CONCLUSIONS: This study provides further evidence for the stability of anorexia nervosa incidence rates. Decreased symptom recognition and changes in service use might have contributed to observed changes in the incidence of bulimia nervosa.

Adolescent↗

Current use of nonsteroidal antiinflammatory drugs and the risk of acute myocardial infarction.

STUDY OBJECTIVE: To evaluate the risk of acute myocardial infarction during current exposure to nonsteroidal antiinflammatory drugs (NSAIDs). DESIGN: Retrospective case-control analysis. SETTING: General practice offices. SUBJECTS: A total of 8688 case patients, aged 89 years or younger, with a first-time acute myocardial infarction and 33,923 control subjects matched on age, sex, calendar time, and general practice attended. INTERVENTION: The United Kingdom General Practice Research Database was searched for potential cases of first-time acute myocardial infarction between January 1995 and April 2001. Control subjects without acute myocardial infarction were identified at random. MEASUREMENTS AND MAIN RESULTS: Exposure to NSAIDs was assessed, and 650 case patients and 2339 control subjects were found to be currently taking NSAIDs. After adjusting for various risk factors for acute myocardial infarction (e.g., hypertension, hyperlipidemia, diabetes mellitus, ischemic heart disease, body mass index, smoking), the relative risk (expressed as odds ratio [OR]) of acute myocardial infarction was 1.07 (95% confidence interval [CI] 0.96-1.19) for subjects with current NSAID exposure compared with those not taking NSAIDs. The adjusted OR for current diclofenac use was 1.23 (95% CI 1.00-1.51), for current ibuprofen use 1.16 (95% CI 0.92-1.46), and for current naproxen use 0.96 (95% CI 0.66-1.38) compared with those not taking NSAIDs. Current aspirin use combined with current NSAID use was associated with a statistically significant risk reduction (adjusted OR 0.74, 95% CI 0.57-0.97), compared with nonuse of NSAIDs and aspirin. Current use of aspirin together with current use of ibuprofen yielded an adjusted OR of 0.69 (95% CI 0.42-1.15). CONCLUSIONS: Our results provide additional evidence that the risk of first-time acute myocardial infarction during current use of NSAIDs is not materially altered. We found no evidence for a reduced cardioprotective effect of aspirin with concomitant NSAID use.

Adult↗

Recombinant hepatitis B vaccine and the risk of multiple sclerosis: a prospective study.

BACKGROUND: A potential link between the recombinant hepatitis B vaccine and an increased risk of multiple sclerosis (MS) has been evaluated in several studies, but some of them have substantial methodologic limitations. METHODS: The authors conducted a nested case-control study within the General Practice Research Database (GPRD) in the United Kingdom. The authors identified patients who had a first MS diagnosis recorded in the GPRD between January 1993 and December 2000. Cases were patients with a diagnosis of MS confirmed through examination of medical records, and with at least 3 years of continuous recording in the GPRD before their date of first symptoms (index date). Up to 10 controls per case were randomly selected, matched on age, sex, practice, and date of joining the practice. Information on receipt of immunizations was obtained from the computer records. RESULTS: The analyses include 163 cases of MS and 1,604 controls. The OR of MS for vaccination within 3 years before the index date compared to no vaccination was 3.1 (95% CI 1.5, 6.3). No increased risk of MS was associated with tetanus and influenza vaccinations. CONCLUSIONS: These findings are consistent with the hypothesis that immunization with the recombinant hepatitis B vaccine is associated with an increased risk of MS, and challenge the idea that the relation between hepatitis B vaccination and risk of MS is well understood.

Adult↗

Antidepressants and the risk of suicidal behaviors.

CONTEXT: The relation between use of antidepressants, especially selective serotonin reuptake inhibitors (SSRIs), and suicidal ideation and behaviors has received considerable public attention recently. The use of such drugs among teenagers has been of particular concern. OBJECTIVE: To estimate the relative risks (RRs) of nonfatal suicidal behavior in patients starting treatment with 1 of 3 antidepressant drugs compared with patients starting treatment with dothiepin. DESIGN AND SETTING: Matched case-control study of patients treated in UK general practices using the UK General Practice Research Database for 1993-1999. PARTICIPANTS: The base population included 159,810 users of the 4 antidepressant drugs. Participants could have used only 1 of these antidepressants and had to have received at least 1 prescription for the study antidepressant within 90 days before their index date (the date of suicidal behavior or ideation for cases and the same date for matched controls). MAIN OUTCOME MEASURES: Frequency of first-time exposure to amitriptyline, fluoxetine, paroxetine, and dothiepin of patients with a recorded diagnosis of first-time nonfatal suicidal behavior or suicide compared with comparable patients who did not exhibit suicidal behavior. RESULTS: After controlling for age, sex, calendar time, and time from first antidepressant prescription to the onset of suicidal behavior, the relative risks for newly diagnosed nonfatal suicidal behavior in 555 cases and 2062 controls were 0.83 (95% confidence interval, [CI] 0.61-1.13) for amitriptyline, 1.16 (95% CI, 0.90-1.50) for fluoxetine, and 1.29 (95% CI, 0.97-1.70) for paroxetine compared with those using dothiepin. The RR for suicidal behavior among patients first prescribed an antidepressant within 1 to 9 days before their index date was 4.07 (95% CI, 2.89-5.74) compared with patients who were first prescribed an antidepressant 90 days or more before their index date. Time since first antidepressant prescription was not, however, a confounder of the relation between specific antidepressants and suicidal behavior since its relation to suicidal behavior was not materially different among users of the 4 study drugs. Similarly for fatal suicide, the RR among patients who were first prescribed an antidepressant within 1 to 9 days before their index date was 38.0 (95% CI, 6.2-231) compared with those who were first prescribed an antidepressant 90 days or more before their index date. There were no significant associations between the use of a particular study antidepressant and the risk of suicide. CONCLUSIONS: The risk of suicidal behavior after starting antidepressant treatment is similar among users of amitriptyline, fluoxetine, and paroxetine compared with the risk among users of dothiepin. The risk of suicidal behavior is increased in the first month after starting antidepressants, especially during the first 1 to 9 days. A possible small increase in risk (bordering statistical significance) among those starting the newest antidepressant, paroxetine, is of a magnitude that could readily be due to uncontrolled confounding by severity of depression. Based on limited information, we also conclude that there is no substantial difference in effect of the 4 drugs on people aged 10 to 19 years.

Adolescent↗

A population-based study of the incidence, cause, and severity of anaphylaxis in the United Kingdom.

BACKGROUND: Anaphylaxis is an acute and potentially fatal systemic reaction usually caused by mast cell-mediated release of histamine. Symptoms can vary in onset, appearance, and severity. Some common symptoms include weakness, dizziness, flushing, angioedema, urticaria, nasal congestion, and sneezing. Severe symptoms include upper respiratory tract obstruction, hypotension, vascular collapse associated with angioedema and urticaria, gastrointestinal distress, cardiovascular arrhythmias, and/or arrest. METHODS: We conducted an observational follow-up study encompassing approximately 8 million person-years based on the UK General Practice Research Database for the period January 1, 1994, to December 31, 1999, which quantified the frequency, type, and severity of a clinical diagnosis of anaphylaxis. RESULTS: Based on 675 cases of anaphylaxis, we estimate the incidence to be 8.4 per 100 000 person-years. Approximately 10% of cases had hypotension and shock that required urgent treatment. The most common causes were insect stings and oral medicines. CONCLUSION: Anaphylaxis is an uncommon illness that has multiple causes and can be life-threatening.

Aged↗